Dedicated high-resolution small animal imaging systems have recently emerged as important new tools for cancer research. Of these systems, x-ray microcomputed tomography (microCT) shows promise as a cost-effective means for detecting and characterizing soft tissue structures, skeletal abnormalities, and tumors in live animals. Existing CT systems provide high-resolution images with excellent sensitivity; however, use of this powerful modality for many important functional studies is limited due to their slower speed of operation (5 to 30 minutes acquisition time) and limited area coverage. To address these limitations, we propose to develop a high speed, high sensitivity, and large area detector for x-ray microCT. The detector will be based on a new high efficiency, low afterglow, structured scintillator coupled to a modified architecture CCD with a specially designed readout to accommodate high frame rates. By the end of the Phase II research we will have developed a fully functional prototype microCT system based on this novel detector. The envisioned system will allow volumetric data acquisition in one second or less, while minimizing the radiation dose to the animal. The efficacy of this system will be demonstrated by imaging tissue vascular physiology and perfusion in organs, as well as by conducting functional physiologic studies in small animals. This new imaging technology has enormous potential in both medical and non-medical applications. The estimated market size for high resolution, reduced afterglow scintillator, high temporal and spatial resolution detector, and other technologies being developed under this program is well over one hundred million dollars. A significant fraction of this market represents areas where the involved technologies will have a major impact. [unreadable] [unreadable] [unreadable]